ASoC: rt5514: Move the auto disable DSP function to set_bias_level()

Move the auto disable DSP function from the widget event "DAPM Pre" to
the set_bias_level() function to avoid the unexpected behavior. While the
SPI was recording using the DAI "rt5514-dsp-cpu-dai", the event "DAPM Pre"
would be manipulated even the DAPM widgets were not connected, and it also
would power off the DSP that cause the DSP buffered data lost. So the auto
disable DSP function should move to the set_bias_level() function to make
sure that it is only manipulated by the DAPM widgets are connected.

Signed-off-by: Oder Chiou <oder_chiou@realtek.com>
Signed-off-by: Mark Brown <broonie@kernel.org>